Quantum information and precision measurement

We describe some applications of quantum information theory to the analysis of quantum limits on measurement sensitivity. A measurement of a weak forc e acting on a quantum system is a determination of a classical parameter ap pearing in the master equation that governs the evolution of the system; li mitations on measurement accuracy arise because it is not possible to disti nguish perfectly among the different possible values of this parameter. Too ls developed in the study of quantum information and computation can be exp loited to improve the precision of physics experiments; examples include su perdense coding, fast database search, and the quantum Fourier transform.